Mathematicians have conjectured since Euclid’s time that there are infinite pairs of prime numbers separated from each other by 2. Despite the fact that primes are separated on average by bigger gaps as numbers increase, evidence suggests that primes continue to appear as “twin primes” (green triangles) no matter how high you go. The illustration above highlights prime numbers, counting from 1 at upper left to 300 at lower right. Below, prime numbers are shown, counting from 1 at upper left t...